Circuit breaker



Feb. 17, 1953 R. BROWN 2,629,036

' CIRCUIT BREAKER Filed March 16, 1950 2 SHEETS-SHEET 1 IN VEN TOR.

ROBE/P T L BROWN M A TTOIQ/VEV Patented Feb. 17, 1953 CIRCUIT BREAKER Robert L. Brown, Lconia, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application March 16, 1950, Serial No. 150,087

6 Claims.

The present invention relates to direct current circuit interruption and more particularly to means for extinguishing arcs therein.

In interrupting direct current electrical circuits, especially at high altitudes and voltages above 30 volts, considerable difficulty is encountered with arcing currents. These arcing currents, unless extinguished quickly will seriously damage the switch contacts and other parts with which they come into contact.

According to the present invention the arcs are forced out by magnetic action along a pair of arc horns and are driven into deion plates. Thus, the arc drop is finally made so great that the applied voltage can no longer maintain the arcs and the current flow is interrupted.

An object of the invention is to provide an improved contactor.

Another object of the invention is to provide improved means for extinguishing arcs.

Another object of the invention is to provide an improved contactor for operation at high altitudes.

Another object is to provide an improved contact making and breaking arrangement.

Another object is to provide an improved magnetic arc blowout arrangement.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawings wherein one embodiment of the invention is illustrated by way of example.

In the drawing:

Figure l is a partial cutaway front view of a contactor embodying the invention.

Figure 2 is an end view of the contactor of Figure 1.

Figure 3 is a side view of the contactor of :Figure 1.

Referring now to the drawings, whereinlik parts have been given the same reference numbers in the several figures, there is shown a base plate I, upon which is mounted operating mechanism 2. The operating mechanism 2 maybe a solenoid, hand-operated or other suitable form of actuating mechanisms which are known to the art and a detailed description has been omitted as it forms no part of the invention.

A contact actuating rod 3 cperatively connected to the operating mechanism 2 extends into an arc chamber 4. The rod 3 carries a bridge contact member 5 secured thereto by a pin 6 and slotted hole 1. A spring 8 biases the bridge member 5 outward from the rod 3. Contacts 9;and l0 are carried. and electrically connected by the bridge member 5. An insulating barrier H is inserted between the contacts 9 and I0 and secured to the actuating rod 3.

The contacts 9 and 10 when actuated to the closed circuit position engage contacts l2 and I3 respectively. The contacts 12 and 13 are attached to one end of respective flared arc horns l4 and [5. The arc horns It and I5 are secured in position by suitable slots IS in a pair of plates H. The plates ll are of a refractory insulating material and form the sides of the arc chamber 4.

A second pair of flared arc horns l8 and [9 are secured in position by suitable slots 20 in the plates l1 and are tied together electrically by a copper bar 2!. In the flared-out area between the pairs of arc horns are deion plates 22, 23 and 2d of electrical conducting material. The deion plates are secured in position and electrically isolated by suitable slots 25 in the plates [1 and grids 25 of refractory insulating material which form the ends for the arc chamber 4. The grids 26 have suitable openings 21 to permit the escape of gases from the are chamber 4.

0n the outside of the insulating plates I! are a pair of soft iron plates 28. External to the two are cavities formed by the aforenoted arrangement is an iron core 29 connecting the iron plates 28 together by means of bolts 30. A three turn series coil 3| is Wrapped around the core 29. One

end of the coil 3! is connected to the arc horn l4 carrying the contact l2. The other end of the coil 3| is connected to input conductor 32. The arc horn 15 carrying the contact I3 is connected to output conductor 33.

The are chamber 4 is mounted on the base I by insulated spacers 34, post 35 and screws 36 and by the screws 30 and iron core 29. A suitable cover 31 may be attached to the base I in any suitable manner. I

In operation when the contacts 9 and ID are in the closed position, the current path is from the input conductor 32, coil 3|, arc horn I4, contact 12, contact 9, bridge 5, contact In, con" tact [3, are horn I5 and output conductor 33. Any current flowing through the unit (either while the contacts are closed or while an arc persists when the contacts are opening) causes the coil 3i to set up a flux in the core 29 that is substantially proportional to the value of the current. This flux is carried along the iron plates 23 and then passes through the air across from one plate to the other. Thus a magnetic field is set up in the arc chamber 4 adjacent to the bridge 5 that is perpendicular to an are that may form on the parting contacts.

The aforenoted flux produces a-force and resultthe bridge to the other bridge contact thence to the other fixed contact. As the contacts separate further, the two arcs will be driven off the ends of the of the bridge and forced to transfer to the two are horns l3 and 59. The current now goes from the arc horn M to are horn l8, then through the bus 2! to are horn l9 and across the arc horn IS.

The arcs are next forced out along the respective arc horns and are driven into the deion plates 22, 23, 24 by the magnetic flux. The are drop is thus finally made so great, due to long arc length, the cathode drop or" each deion plate and the deionization action of all the relatively cool surfaces, that the applied voltage can no longer maintain the arcs and thus the current flow is interrupted.

The insulated grids 26 forming the ends of the arc chamber 4 add the final additional deionization that might be needed for exceeding heavy currents at high altitudes and also to lessen the chance of an arc flashing out the flared opening of the arc horns and transferring to the case of the unit. Also the openings 27 in the grid permit the escape of gases.

As an additional safety feature, the insulating barrier ll prevents arcing from occurring between. the fixed contacts 12 and 13 when small. currents are interrupted at high altitudes. Upon. arcs. of small currents being drawn between the. separating contacts, there will be little or no magnetic forces on them and thus instead of moving apart might combine to bridge the fixed gap between the contacts [2- and [3 with an uncontrollable arc.

Although only one embodiment of the inven tion. has been illustrated and described, various changes in the form and relative arrangement of the parts, which. will now appear to those skilled in the art, may be made without departing from the scope of the invention.

What is claimed is:

1. In a circuit interrupter, a pair of stationary contacts spaced apart from each other, movable contact means for bridging said contacts, a first pair of opposite extending outwardly flared arc horns, the inner ends of said are horns engaging said stationary contacts, a second pair of op positely extending outwardly flared arev horns positioned opposite from said first arc horns, the inner ends of said second arc. horns being adjacent to said bridging means, means for connecting the outer ends of said second arc horns together electrically, and magnetic means including a coil in series with said contacts to bias an are that may be formed between said contacts and said bridging means outward along said are horns thereby to increase the arc length.

2. The combination as described in claim 1 and including an insulating barrier between said stationary contacts.

3. The combination as described in claim 1 and including a supporting structure for said are horns comprising a pair of plates of refractory insulating material having slots therein for supporting said are horns and forming an arc chamber.

4. The combination as described in claim 1 and. including an arc chamber comprising a pair of side plates of refractory insulating material, and end grid plates of refractory insulating material having opening therein to permit the escape of gases.

5. Ina contactor, a pair of symmetrical opposite extending outwardly flared arc horns having contact members on the inner ends thereof, said contact members being spaced apart, movable contact means for bridgingv said contact members, a second pair of symmetrical opposite extending flared arc horns positioned opposite from said first arc horns with the inner ends adjacent to said movable contact means, electrical conducting means for interconnecting said second pair. of arc hornsdeion plates positioned in the flared-out area between said pairs of arc horns, and means for producing a magnetic flux perpendicular to the arcs drawn between said contact means to drive said arcs outward along said are horns into said deion plates.

6. In a circuit interrupter, a first pair of flared opposite extending arc horns having stationary contact members on the adjacent ends thereof, a pair of relatively movable contact members adapted for engaging said stationary contact members, electrical conducting means for connecting said movable contact members, a. second pair of flared opposite extendin are horns positioned opposite of said first pair of archorns, means for connecting said second arc horns in series, deion plates positioned in the flared area between said pairs of arc horns, and magnetic means for biasing an are formed between saidv stationary and movable contacts outward along said are horns into said deion plates.

ROBERT L. BROWN.

REFERENCES CITED The following references are of record in the filev of: this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Germany June 4, 1934 Number Number 

